The trading of illicit goods in dark net marketplaces is a significant and growing global problem. This paper describes the findings from a study which involved the use of Work Domain Analysis in conjunction with a node breaking process to identify interventions designed to disrupt trading in dark net marketplaces. The analysis identified a series of critical disruption points and opportunities for disrupting dark net trading, including strategies to disrupt critical functions such as marketplace administration, reputation management, and product management. The analysis also showcases the potential use of Human Factors and Ergonomics for disrupting, as well as optimising, complex sociotechnical systems. The benefits of using Human Factors and Ergonomics to disrupt complex systems, as well as optimise them, are discussed along with potential application areas.